Reaseach Of Land Surface Design Of City Park Based On The Sequestration Potential Of Soil

Soil organic carbon(SOC)mineralization is a significant process in soil carbon cycling in the terrestrial ecosystem,which is closely related to the soil nutrient release and global climate change.Function of urban soil as an ecosystem has degenerated due to severe human disturbances,which deeply influence the geochemical cycles,especially the carbon cycle,in urban eco-environments.In order to explore the variation in SOC mineralization and SOC sequestration potential under various land cover types,we collected soil samples from five typical land cover types,i.e.,grass-covered,shrub-covered,street tree-planted,grass-planting brick,and impervious surface,in the Olympic Forestry Park in the summer of2016.SOC mineralization and physico-chemical properties,such as pH,particle constitution,and nutrient content,of all soil samples were measured.After the experiment,we analyzed the variation in SOC mineralization under various land cover types and the relationship between SOC mineralization and soil physico-chemical properties.The results showed that the SOC mineralization of urban soil was stronger at the early incubation period than that at the late incubation period,the same trend also favored the soil organic carbon mineralization in natural ecosystems.However,the relatively significant differences in daily and cumulative amount of SOC mineralization were observed among those 5 types of land cover,especially in the early incubation period.Both the daily and the cumulative amount of SOC mineralization under shrub-covered,street tree planted and grass-planting brick were stronger than those under the other two land covers,which was of the basic agreement with the characteristic of SOC content.SOC mineralization of all the soil samples in this experiment followed the first-order kinetic equation well.Simulation results showed that the SOC sequestration ability was relatively weak under impervious surface,grass-planting brick and street tree planted,while the SOC sequestration ability under the grass covered and the shrub covered was both relatively strong.In contrast with the SOC mineralization,the ability of SOC sequestration was inconsistent with the characteristic of SOC content,which may be deeply influenced by human distribution and input of additional organic carbon.As for the variation of SOC mineralization along layer depth,there was no significant difference among 3 layers(0-15,15-30,30-45 cm)under impervious surface,while the SOC mineralization of top layer under other land cover types was greater than that of lower layers as a whole,especially the mineralization of the soil under grass-planting brick and street treeplanted.Correlation analysis suggested that the SOC content was the main constraint of SOC mineralization,while other chemico-physical properties,including pH,nutrient content and clay content,may indirectly influence SOC mineralization by impacting SOC content and microbial activity.Based on the quantitative analysis,the author estimated the soil carbon sequestration capacity of the Madian Park using the carbon density method,and we obtained the surface layer(0—45 cm)soil carbon sequestration capacity of the Madian Park is 184.4 t.After that,we simulated the variation of the soil carbon sequestration capacity of the park in two assumptive cases.The results of the analysis reveal that using the grass-planting brick and planting more shrub can be effective for improving the soil carbon sequestration capacity.Finally,in the case of the children's play area of Madian Park,after we do the eco-renovation for the land cover types based on the investigation of the surrounding environment,users,paving materials,plant configuration,etc,for the purpose of providing ideas for landscape design,improving the carbon sequestration capacity of the soil in urban area and providing the scientific basis for improvement of the ecosystem service of the urban park.